<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<script>
	var arr=[[1,2,3,4],[3,4,5,6],[5,6,7,8]];
	var newarr=arr[0].map(function(currentValue,index,currentArr){
		return arr.map(function(cv,i,ca){
			return cv[index];
		});
	});
	console.log(newarr);
	
	
</script>	
</body>
</html>
